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Acta Mechanica Solida Sinica 2014年第2期27卷 202-209页

作者： hossein Roostai Mohammad Haghpanahi Department of Mechanical Engineering Iran University of Science & Technology (IUST)

The aim of this paper is to study the free transverse vibration of a hanging nonuni- form nanoscale tube. The analysis procedure is based on nonlocal elasticity theory with surface effects. The nonlocal elasticity theory states that the stress at a point is a function of strains at all points in the continuum. This theory becomes significant for small-length scale objects such as micro- and nanostructures. The effects of nonlocality, surface energy and axial force on the natural frequencies of the nanotube are investigated. In this study, analytical solutions are formulated for a clamped-free Euler-Bernoulli beam to study the free vibration of nanoscale tubes.

关键词： nonlocal elasticity theory vibration surface effects nanoscale tube

Effect of residual structural strain caused by the addition of Co3O4 nanoparticles on the structural, hardness and magnetic properties of an Al/Co3O4 nanocomposite produced by powder metallurgy

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International Journal of Minerals,Metallurgy and Materials 2020年第3期27卷 384-390页

作者： Seyed Rahim Kiahosseini hossein Ahmadian Department of Engineering Damghan Branch Islamic Azad University

Al composites are of interest due to their appropriate ratio of strength to *** our research,an Al/Co3O4 nanocomposite was generated using a sintering *** powders of Al with various Co3O4 nanoparticle contents(0 wt%,0.5 wt%,1.0 wt%,1.5 wt%,2.0 wt%,and2.5 wt%)were first blended using planetary milling for 30 min,and compressed in a cylindrical steel mold with a diameter of 1 cm and a height of5 cm at a pressure of 80 *** samples were evaluated with X-ray diffractometry(XRD),scanning electron microscopy(SEM),Vickers hardness,and a vibrating sample magnetometer(VSM).Although the crystallite size of the Al particles remained constant at 7–10 nm,the accumulation of nanoparticles in the Al particle interspace increased the structural tensile strain from 0.0045 to 0.0063,the hardness from HV 28 to HV 52 and the magnetic saturation from 0.044 to 0.404 emu/g with an increase in Co3O4 nanoparticle content from 0 wt%to 2.5 wt%.

关键词： Residual strain Vickers hardness vibrating sample magnetometer scanning electron microscopy

Mechanical characterization of Mg-B4C nanocomposite fabricated at different strain rates

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International Journal of Minerals,Metallurgy and Materials 2020年第2期27卷 252-263页

作者： Gholam hossein Majzoobi Kaveh Rahmani Mechanical Engineering Department Bu-Ali Sina University

Magnesium has wide application in *** main purpose of this investigation was to improve the properties of magnesium by reinforcing it using B4C *** reinforced nanocomposites were fabricated using a powder compaction technique for 0,1.5vol%,3vol%,5vol%,and 10vol% of *** compaction was conducted using a split Hopkinson bar(SHB),drop hammer(DH),and Instron to reach different compaction loading *** compressive stress–strain curves of the samples were captured from quasi-static and dynamic tests carried out using an Instron and split Hopkinson pressure bar,*** revealed that,to achieve the highest improvement in ultimate strength,the contents of B4C were 1.5vol%,3vol%,and 3vol% for Instron,DH,and SHB,*** results also indicated that the effect of compaction type on the quasi-static strength of the samples was not as significant,although its effect on the dynamic strength of the samples was *** improvement in ultimate strength obtained from the quasi-static stress–strain curves of the samples(compared to pure Mg)varied from 9.9% for DH to 24% for *** dynamic strength of the samples was improved(with respect to pure Mg)by 73%,116%,and 141%for the specimens compacted by Instron,DH,and SHB,*** improvement in strength was believed to be due to strengthening mechanisms,friction,adiabatic heating,and shock waves.

关键词： powder compaction B4C magnesium strain rate ultimate strength sintering

A simulation study on p-doping level of polymer host material in P3HT:PCBM bulk heterojunction solar cells

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Chinese Physics B 2017年第4期26卷 508-512页

作者： hossein Movla Mohammad Babazadeh Azar Aytash Co. Technology IncubatorUniversity of TabrizTabrizIran

In this study,we investigate the influence of doping on the charge transfer and device characteristics parameters in the bulk heterojunction solar cells based on poly（3-hexylthiophene）（P3HT） and a methanofuUerene derivative（PCBM）.Organic semiconductors are also known to be not pure and they have defects and impurities,some of them are being charged and act as p-type or n-type *** of the solar cell characteristics parameters versus the p-doping level have been done at three different n-dopings（N_d） that consist of 5 × 10^（17） cm^（-3）,10^（18） cm^（-3）,and 5 × 10^（18） cm^（-3）.We perform the analysis of the doping concentration through the drift-diffusion model,and calculate the current and voltage doping *** find that at three different n-dopant levels,optimum p-type doping is about N_p = 6 × 10^（18） cm^（-3）.Simulation results have shown that by increasing doping level,V_（oc） monotonically increases by *** efficiency reaches its maximum at somewhat higher doping as FF has its peak at N_p = 3 × 10^（18） cm^（-3）.Moreover,this paper demonstrates that the optimum value for the p-doping is about N_p = 6 × 10^（18） cm^（-3） and optimum value for n-dopant is N_d = 10^（18） cm^（-3）,*** simulated results confirm that doping considerably affects the performance of organic solar cells.

关键词： organic photovoltaics charge transport doping finite difference method

Secure Resource Allocation in Device-to-Device Communications Underlaying Cellular Networks

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China Communications 2022年第8期19卷 149-167页

作者： hossein Ghavami Bahareh Akhbari Faculty of Electrical Engineering K.N.Toosi University of TechnologyTehranIran

With increasing the demand for transmitting secure information in wireless networks,deviceto-device(D2D)communication has great potential to improve system *** a well-known security risk is eavesdropping in D2D communication,ensuring information security is quite *** this paper,we first obtain the closed-forms of the secrecy outage probability(SOP)and the secrecy ergodic capacity(SEC)for direct and decodeand-forward(DF)relay *** results are presented to verify the theoretical results,and these results show the cases that the DF relay mode improves security performance compared to the direct mode at long distances between the transmitter and receiver ***,we look into the optimization problems of secure resource allocation in D2D communication to maximize the SEC and to minimize the SOP by considering the strictly positive secrecy capacity constraint as a mixed-integer non-linear programming(MINLP)*** the continue,we convert the MINLP to convex ***,we solve this program with a dual method and obtain an optimal solution in the direct and DF relay modes.

关键词： D2D communication Secrecy ergodic capacity Secrecy outage probability Secrecy resource allocation Convex optimization

Estimating oak forest parameters in the western mountains of Iran using satellite-based vegetation indices

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Journal of Forestry Research 2020年第2期31卷 541-552页

作者： Adel Nouri Bahman Kiani Mohammad hossein Hakimi Mohammad hossein Mokhtari Department of Forest Sciences Faculty of Natural ResourcesYazd UniversityYazdIslamic Republic of Iran Department of Desert Management Faculty of Natural ResourcesYazd UniversityYazdIslamic Republic of Iran

Remote sensing is an important tool for studying and modeling forest *** indices obtained from Landsat-8 remotely sensed data were used to estimate the forest parameters in the western mountains of *** sample points were selected on the map of Bayangan County,Kermanshah province,*** each point,a cluster of five rectangular plots of 8100 m2 and 200 m apart was *** clusters were primarily sampled to determine the variance of the forest *** coefficient of variation was used as a criterion for sample *** density,canopy cover and basal area per hectare were calculated for each *** indices were extracted fromthe Landsat-8 images for each *** linear and nonlinear regressions were conducted to develop the *** models were validated using an independent data *** of model parameters was statistically *** results showed that Normalized difference vegetation index(NDVI)and Transformed normalized difference vegetation index(TNDVI)followed by Simple ratio vegetation index(SRVI)were the best predictors,explaining up to 91%of the variations with high *** NDVI,Soil adjusted vegetation index 2(SAVI2)and SRVI,the cubic model was more appropriate than the linear model for predicting the forest *** this model,the R-square value increased while NRMSE decreased *** Infrared percentage vegetation index(IPVI),the quadratic model was better,but,for other vegetation indices,nonlinear models were not superior to linear ***,it can be concluded that Landsat-8 imagery is suitable for predicting forest parameters in the oak forests of western *** course,large plots must be selected,and pre-classification is necessary to gain accurate and precise estimations.

关键词： Basal area Canopy cover Density Landsat-8 Modeling

Plant diversity of Hyrcanian relict forests:An annotated checklist,chorology and threat categories of endemic and near endemic vascular plant species

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Plant Diversity 2022年第1期44卷 39-69页

作者： Atefeh Ghorbanalizadeh hossein Akhani Halophytes and C4 Plants Research Laboratory Department of Plant SciencesSchool of BiologyCollege of SciencesUniversity of TehranP.O.Box 14155-6455TehranIran

In this paper a critical annotated checklist of 256 endemic and near endemic species belonging to 152 genera and 50 families of flowering plants known from Hyrcanian relict forests is *** maps of taxa,elevational range,number of known records,chorotypes,life forms,IUCN threat categories and habitat types are also *** chorotypes are categorized into eight main patterns:1)the Omni-Hyrcanian pattern(OH),2)West Hyrcanian pattern(WH),3)Manjil-Rudbar pattern(MR),4)Central Hyrcanian pattern(CH),5)Central and East Hyrcanian pattern(CEH),6)East Hyrcanian pattern(EH),7)Alborz-Hyrcanian pattern(AH),and 8)Euxino-Hyrcanian pattern(XH).The richness and distribution maps were generated based on 5408 records gained from herbarium specimens and literature *** life form spectra show that the majority of taxa(54.7%)belong to hemicryptophytes,followed by the tuberous,bulbous and parasitic geophytes with 45 species(17.6%)and phanerophytes with 28 taxa(10.9%).The conservation status of species according to IUCN criteria indicates that 30 taxa are Critically Endangered,52 taxa Endangered,30 taxa Vulnerable,25 taxa Near Threatened and 81 taxa are of Least *** present data were not sufficient to evaluate 38 taxa that are categorized here as Data *** new combination of Leutea translucens(=Peucedanum translucens)is validated with inclusion of Peucedanum hyrcanicum as its *** disjunct occurrence of the Caucasian species Gentiana grossheimii is reported from the eastern parts of the Hyrcanian forests in Iran for the first *** conclude that(i)the Hyrcanian forests and associated habitats in the northern slopes of the Alborz Mountains harbour tremendous floristic diversity of high conservation priority,and(ii)the Hyrcanian forest zone is an important and unique center of endemism within the Euro-Siberian region that should be considered a floristic province with a large number of relict species.

关键词： Biodiversity Distribution pattern Endemic plant Hyrcanian forests IUCN category

A functorial approach to categorical resolutions

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Science China Mathematics 2020年第10期63卷 2005-2016页

作者： Rasool Hafezi Mohammad hossein Keshavarz School of Mathematics Institute for Research in Fundamental Sciences(IPM)Tehran 19395-5746Iran

Using a relative version of Auslander’s formula,we give a functorial approach to show that the bounded derived category of every Artin algebra admits a categorical ***,in particular,implies that the bounded derived categories of Artin algebras of finite global dimension determine bounded derived categories of all Artin ***,this paper can be considered as a typical application of functor categories,introduced in representation theory by Auslander(1971),to categorical resolutions.

关键词： categorical resolutions Artin algebras Auslander’s formula

Transferring information through a mixed-five-spin chain channel

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Chinese Physics B 2016年第8期25卷 53-58页

作者： Hamid Arian Zad hossein Movahhedian Department of Physics Shahrood University of Technology

We initially introduce one-dimensional mixed-five-spin chain with Ising-XY model which includes mixture of spins-1/2 and spins-1. Here, it is considered that nearest spins（1, 1/2） have Ising-type interaction and nearest spins（1/2, 1/2）have both XY-type and Dzyaloshinskii–Moriya（DM） interactions together. Nearest spins（1, 1） have X X Heisenberg interaction. This system is in the vicinity of an external homogeneous magnetic field B in thermal equilibrium state. We promote the quantum information transmitting protocol verified for a normal spin chain with simple model（refer to Rossini D, Giovannetti V and Fazio R 2007 Int. J. Quantum Infor. 5 439）（widely in reference： Giovannetti V and Fazio R 2005 Phys. Rev. A 71 032314） by means of considering the suggested mixed-five-spin chain as a quantum communication channel for transmitting both qubits and qutrits ideally. Hence, we investigate some useful quantities such as quantum capacity and quantum information transmission rate for the system. Finally, we conclude that, when the DM interaction between spins（1/2, 1/2） increases the system is a more ideal channel for transmitting information.

关键词： Dzyaloshinskii-Moriya interaction XX Heisenberg interaction communication channel transmission rate

Reduction of the wind erosion potential in dried-up lakebeds using artificial biocrusts

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Frontiers of Earth Science 2022年第4期16卷 865-875页

作者： hossein KHEIRFAM Maryam ROOHI Department of Range and Watershed Management Faculty of Natural ResourcesUrmia UniversityUrmia ***Iran Department of Environmental Sciences Urmia Lake Research InstituteUrmia UniversityUrmia ***Iran Microbiology Laboratory Expert Artemia&Aquaculture Research InstituteUrmia UniversityUrmia ***Iran

The artificial creation of biocrusts can be a rapid and pervasive solution to reduce wind erosion potential(WEP)in dried-up lakes(e.g.,Lake Urmia).So,in this study,we created a biocrust by the inoculation of bacteria and cyanobacteria on trays filled by soils collected from the dried-up bed of Lake Urmia,Iran,to reduce WEP in laboratory *** used the wind erodible fraction of soil(EF)and soil crust factor(SCF)equations to calculate the WEP of the treated *** and SCF were decreased(p<0.05)through applying the co-inoculation of bacteria and cyanobacteria by 5.6%and 10.57%,respectively,as compared to the control;also,the"cyanobacteria alone"inoculation decreased EF by 3.9%.Our results showed that the artificial biocrusts created by soil inoculation,especially with the co-using of bacteria and cyanobacteria,significantly reduced the WEP of a newly dried-up ***,we found that inoculation decreased the WEP of the study soil by increasing the soil organic matter content from 3.7 to 5 *** to scanning electron microscopy images,the inoculated microorganisms,especially cyanobacteria,improved soil aggregation by their exopolysaccharides and filaments;thus,they can be used with other factors to estimate the soil erodibility in well-developed *** inoculation technique could be considered as a rapid strategy in stabilizing lakebeds against wind ***,it should be confirmed after additional experiments using wind tunnels under natural conditions.

关键词： biological soil crust dried-up lakes dust storms flowing-sands soil cyanobacteria